|Publication number||US7427947 B1|
|Application number||US 11/820,033|
|Publication date||Sep 23, 2008|
|Filing date||May 30, 2007|
|Priority date||May 30, 2007|
|Publication number||11820033, 820033, US 7427947 B1, US 7427947B1, US-B1-7427947, US7427947 B1, US7427947B1|
|Inventors||James Dark, James Buscemi, Scott Burkholder|
|Original Assignee||The United States Of America As Represented By The Secretary Of The Navy|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (20), Non-Patent Citations (2), Referenced by (16), Classifications (26), Legal Events (4)|
|External Links: USPTO, USPTO Assignment, Espacenet|
1. Field of the Invention
The invention generally relates to the field of computer software particularly to an improved method of providing aircrew decision aids for use in determining the optimum placement of an Electronic Attack (EA) aircraft. The core of the invention is a software program that will dynamically provide the EA flight crew situational awareness regarding a threat emitter's coverage relative to the position of the EA aircraft and to the position of protected entities (PE). The software program generates information to provide visual cues representing a Jam Acceptability Region (JAR) contour and a Jam Assessment Strobe (JAS) for display via designated aircraft cockpit processors and devices. The JAR and JAS will aid the EA aircrew in assessing the effectiveness of a given jamming approach and assists in determining the optimum flight path for both the PE and EA. The optimized flight paths will minimize exposure to threat emitters allowing accomplishment of the mission.
2. Description of the Prior Art
Electronic Warfare (EW) tactics employed by EA aircraft strive to direct electromagnetic energy into a threat radar receiver with sufficient power to prevent the threat radar receiver from accurately detecting or tracking the PE. EW includes the basic concepts of Noise Jamming and Deception Jamming. Key to the successful jamming effort is generating a signal that exceeds the expected target return signal seen by the threat receiver and concentrating the radar jamming signal in the direction of the threat receiver antenna. Barrage noise jamming floods the threat radar receiver with massive amounts of electronic emissions and significantly degrades low technology threat receiver performance. With the evolution of advanced radar concepts the noise jamming approach is less effective against high technology threat emitters. Advanced technology threat radar emitters have led to tuning the EA jamming frequency to match the frequency of the threat emitter and to follow any frequency hopping or other frequency agile characteristics the threat emitter may employ. Deception jamming requires the EA platform to generate a signal that is similar to the target return signal the threat receiving system expects while modifying target characteristics such as return signal strength, range, heading, velocity or acceleration. Overcoming multiple threat emitters employing advanced radar techniques, while transitioning a hostile area and providing protection jamming is a high workload environment for an aircrew. Cockpit display information and aircrew decision aids are required to improve situational awareness for the EA aircrew. It is an objective of this invention to reduce aircrew workload by providing decision aids.
Systems to aid the EA flight crew decision making process in positioning the jamming source carried by the EA are in need of improvement. Current aids available to EA flight crew provide text and rudimentary visual cues depicting gross EA position relative to threat receiver position. Current EA systems force the flight crew to manually incorporate current PE position relative to the position of the EA and threat receiver, then forces the aircrew to manually determine the optimum EW countermeasure to employ driving up aircrew workload. Current systems are incapable of fusing EA jamming capability with projected threat emitter performance information in order to obtain optimal geometrical positioning of the EA relative to threat emitters. The novel method of combining threat emitter system characteristics with EA aircraft capabilities while simultaneously incorporating PE position in a single display format greatly reduces EA aircrew workload and makes the EA more effective.
The preferred embodiment is a software program to generate the information to display a Jam Acceptability Region (JAR) and a Jam Assessment Strobe (JAS) for a multitude of ground based threat emitters updated in real-time. The JAR and JAS are composed of a threat emitter system susceptibility area based on the position of the Protected Entities (PE) and the Electronic Attack (EA) position. The JAR and JAS provides the EA aircrew visual information depicting the current position of the EA aircraft in relationship to ground based threat emitters and in relationship to the accompanied PE. The PE is the aircraft in need of protection jamming. Electronic Warfare (EW) employs tactics to direct electromagnetic energy into the enemy radar receiver to prevent the receiver from accurately detecting the PE. Key to successful radar jamming is obtaining the proper Signal to Noise (S-N) ratio threshold. One of the most critical factors in achieving this S-N ratio is placing the EA jamming signal in the correct geometric position to blind the threat receiver while the threat antenna is slewed in the direction of the PE. The Jam Assessment software program that is the preferred embodiment of this invention is a real-time software application that will be employed by the EA aircrew during prosecution of their tactical mission. The Jam Assessment software program provides the aircrew with visual cues that enable the flight crew to ascertain current jamming effectiveness. The Jam Assessment software program receives as input EA and PE positional information. The performance characteristics of the threat emitter and EA jamming capabilities are also received as input to the Jam Assessment software program. The information received as input is processed by designated computers on board the EA aircraft and used to generate the visual cues that allow an assessment of jam effectiveness.
For the EA to determine its instantaneous optimum position it must continually ascertain the position of the PE in relationship to each threat emitter and mathematically generate a JAR along with its own position within the JAR. The Jam Assessment software program must account for the interaction of the JAR and the PE position as the PE transits its intended flight path. The Jam Assessment software program blends the position of the EA aircraft and PE aircraft with the information residing in an electronic library designated as an Electronic Order of Battle (EOB). The positional and EOB information are used to generate the visual cues that allow an assessment of jam effectiveness.
The Jam Assessment software program has at its core a JAR processing algorithm executed on designated aircraft computers driving designated display hardware to provide the aircrew with improved situational awareness using visual cues in the form of JAR and JAS symbols.
Broadly stated, the present invention comprises a method and software module that efficiently and simultaneously receives disparate information and transforms the disparate information into usable graphical displays. The graphical displays convey information that is used to position the EA relative to a threat emitter system. A typical threat emitter system is composed of an antenna, a transmitter, a receiver, a mechanism to position the antenna, electronics to process information received and a user interface. Key to the success of any radar jamming technique is exceeding the Signal to Noise ratio threshold that is an inherent characteristic of the threat emitter system. When the noise signal generated by the EA exceeds the signal return of the PE you have defeated the threat emitter system. Likewise, if the EA generates a stronger yet similar signal to the actual return signal of the PE while shifting a PE parameter, such as range or speed, the threat emitter system will be deceived, masking the true position of the PE. Generating a jamming signal to mask the true position, speed or course of the PE degrades acquisition and tracking performance in the threat emitter system.
Generally, threat radar coverage is viewed as the instantaneous threat radar volume swept vertically and horizontally over time through azimuth and elevation limits defined by the threat radar antenna mount. Multiple three-dimensional concentric ellipsoids extend from the transmitting antenna and compose the threat radar volume. The threat radar volume is composed of a main-lobe ellipsoid, numerous side-lobe ellipsoids and numerous back-lobe ellipsoids. The main-lobe ellipsoid extends much farther than any side-lobe ellipsoid or back-lobe ellipsoid. The main-lobe ellipsoid is the primary beam that is swept across a target to generate a return signal strong enough to be detected by a threat receiver. One critical factor in successful radar jamming is placing the jamming signal emitted by the EA in a position to enter the threat receiver via the threat antenna while the threat antenna is slewed in the direction of the PE.
In addition to the geometric relationship (bearing relationship) of the EA and the PE to the threat emitter system other factors also determine the effectiveness of the threat emitter system. The other factors are the jamming technique and the jamming tactic employed by the EA. Two representative jamming techniques are Preemptive Assignment (PA) and Reactive Assignment (RA). The PA technique is invoked when the threat emitter characteristics and threat emitter location are known before the mission is undertaken. The RA technique is employed when an unexpected threat emitter or threat emitter wave form are encountered during a mission requiring the EA to adapt to the threat. Generally, the PA technique results in Jam Acceptability Region (JAR) contours that are smaller in area and shorter in range relative to the JAR contours associated with the RA technique. A JAR is defined as the family of positions an EA may occupy and still provide effective jamming to protect the PE. The difference in area and range, PA relative to RA, is attributed to the relationship of bandwidth to power. When an EA jams the entire known PA bandwidth for a planned threat emitter lower EA jam power is applied to any specific threat emitter frequency. When the EA detects a threat emitter the RA jamming power may be narrowed into a band focused on the frequency of interest resulting in a JAR that has a larger area and a longer range, relative to the PA JAR.
Three representative jamming tactics are associated with three JAR contours, irrespective of activating either a PA or an RA technique. Referring to
The S tactic results in a conically shaped JAR directly related to the side lobe radiation pattern of the threat emitter antenna. The EA is effective anywhere within JAR 115 provided the EA does not exceed the AS range 135.
Successful jamming of the threat emitter system using the S tactic requires the EA to be within the side-lobe volume of the threat emitter while the main lobe of the threat emitter volume encompasses the PE. While the S tactic increases the standoff range for the EA, relative to the O tactic, the EA is effective only while maintaining the geometric relationship to the PE and to the threat emitter.
The I tactic results in a conically shaped JAR directly related to the main lobe radiation pattern of the threat emitter antenna. A two dimensional depiction of the conically shaped JAR contour is depicted in
The I tactic provides an improved EA stand off range from the threat antenna but requires that a stringent geometric relationship be maintained between the EA and PE to the threat antenna. The I tactic requires that the EA and PE are in alignment while the threat antenna main-lobe volume encompasses the PE, hence the narrowness of JAR 120.
Each of the techniques and tactics are combined in all permutations to produce a set of jamming approaches to degrade the performance of the threat emitter system. The jamming approaches are: Preemptive Assignment—Out of Alignment (PAO), Preemptive Assignment—In Side-Lobe Alignment (PAS), Preemptive Assignment—In Main-Lobe Alignment (PAI), Reactive Assignment—Out of Alignment (RAO), Reactive Assignment—In Side-Lobe Alignment (RAS), and Reactive Assignment—In Main-Lobe Alignment (RAI).
A given EA jamming approach has a determinable impact upon the threat emitter radar coverage. The JAR represents a volume of space in which the EA may position itself to provide effective jamming to mask the PE or deceive the threat emitter system regarding the true course and speed of the PE. Generating the JAR, assessing jamming effectiveness, determining optimum positioning of the EA and conveying this information to the EA aircrew are objectives of this invention.
Optionally, placing the EA 240 within PAS-JAR 230 would enable the PAS jamming approach that would provide adequate protection for PE 205. It should be noted that the PAS jamming approach would place the EA 240 closer to the threat emitter 160.
Optionally, placing the EA 240 within PAO-JAR 250 would enable the PAO jamming approach that would provide adequate protection for PE 205. It should be noted that the PAO jamming approach would place the EA 240 even closer to the threat emitter 160.
Relying on the bearing relationships between the EA and PE to the threat emitter and the maximum range of the threat emitter, the software performs a check 415 to determine if the PE is within the maximum range of the threat emitter. If the PE is not within the range of the threat emitter a no jam required flag is set 420, the displays are cleared of stale information in step 465, then step 475 determines program end 480 or directs program control to step 410 for a subsequent iteration.
If the PE is within range of the threat emitter, step 425 determines the alignment of the EA, PE and threat emitter. If the result of alignment check 425 is that the EA, PE and threat emitter are in alignment then a flag is set 430 to “I”. If alignment check 425 returns an out of alignment result then a side lobe check is made at step 435. If the side lobe check 435 result is positive for the PE being within the side lobe then the alignment flag is set to “S” 445. If the side lobe check 435 is negative the assumption is the EA, PE and threat emitter are Out of alignment and the alignment flag is set to “O” 440.
The software must now determine whether to invoke RA processing or PA processing. The software then checks for activation of RA 450, a check to determine whether the EA has detected a threat emitter waveform. If the result of RA 450 check is positive, the threat emitter is not in the EOB, then RA processing 455 is called. Refer to
The limits of threat emitter coverage, in the presence of jamming, obtained from the JATO power equation yield a JAR contour. The constants and variable definitions for the JATO power equation 1-1 are provided below.
Rmax=Maximum effective range for a threat emitter
GRT=Receiver Antenna Gain
σ=Radar Cross Section
S/N=Signal to Noise Ratio
Lrp=Receiver Processing Loss
k·T·Nf=constant for transmission noise figure
GJR=Jammer Receiver Antenna Gain
GRJ=Jammer Receiver Gain
RJ=Range of Jammer
LP=Jammer Processing Loss
The accuracy of Rmax is dependent upon the accuracy of the critical threat attribute parameters drawn from the EOB, the positional information of the threat emitter system, the positional information of the EA and the EA jamming approach parameters.
Equation 1-1 is a variation of the well known radar range equation. Equation 1-1 is invoked for each jamming approach, for each threat emitter, and for changing PE and EA positions.
If the S flag is set then a check 565 is made to determine whether the PE is within the RAS range of the threat emitter. If the PE is within range of the threat emitter the Jam flag is set to RAS alarm 585, the JAS color is set to red 590 and the RA routine is exited 598. If the PE is not within the range of the threat emitter then the Jam flag is set to RAS 580 and the JAS color is set to green 595 and the RA routine is exited 598.
If the S flag was not set then the alignment must be Out of alignment (O). A check 560 is made to determine whether the PE is within the RAO range of the threat emitter. If the PE is within range of the threat emitter the Jam flag is set to RAO alarm 575, the JAS color is set to red 576 and the RA routine is exited 598. If the PE is not within the range of the threat emitter then the Jam flag is set to RAO 570 and the JAS color is set to green 571 and the RA routine is exited 598.
If the S flag is set then a check 665 is made to determine whether the PE is within the PAS range of the threat emitter. If the PE is within range of the threat emitter the Jam flag is set to PAS alarm 685, the JAS color is set to red 690 and the PA routine is exited 698. If the PE is not within the range of the threat emitter then the Jam flag is set to PAS 680 and the JAS color is set to green 695 and the PA routine is exited 698.
If the S flag was not set then the alignment must be Out of alignment (O). A check 660 is made to determine whether the PE is within the PAO range of the threat emitter. If the PE is within range of the threat emitter the Jam flag is set to PAO alarm 675, the JAS color is set to red 676 and the PA routine is exited 698. If the PE is not within the range of the threat emitter then the Jam flag is set to PAO 670 and the JAS color is set to green 671 and the PA routine is exited 698.
Typical displays are JARs with PE and EA positions plotted with respect to their last known or extrapolated position and a color coded Jam Assessment Strobe (JAS) indicating jamming effectiveness. The length of the JAS represents the maximum effective range for a threat emitter experiencing EA jamming. Each jamming approach (RAO, RAI, RAS, PAO, PAS, PAI) affects the maximum detection range of the emitter adversely. Color coding the JAR contours and JAS is a user preference and is limited by the display processor and the properties of the display hardware residing in the EA aircraft.
In the event multiple threat emitters have overlapping coverage the overlap volume can be determined. Refer to
Another embodiment of this invention generates a display format as depicted in
Providing information to the EA aircrew related to detected threat emitters not currently assigned a jamming approach is critical to overall situational awareness.
The aircrew controls the display format posted by the aircraft display processor via designated aircraft interfaces. Depending on the need, the aircrew display options include the JAR contours, the JAS or a combined JAR JAS display format. The software algorithm and method described above is suitable for implementation upon any number of electronic warfare systems and architectures. It is not necessary to limit the implementation of the preferred embodiment to currently existing aircraft computers, aircraft interfaces or electronic warfare capabilities.
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|U.S. Classification||342/173, 342/14, 342/175, 342/180, 342/176, 342/13, 342/165, 342/181, 342/89, 342/20, 342/195|
|International Classification||G01S7/38, G01S13/00, G01S7/40, G01S7/00|
|Cooperative Classification||G01S7/38, G01S7/021, H04K3/45, H04K2203/22, H04K3/94, G01S7/04|
|European Classification||H04K3/94, H04K3/45, G01S7/02A, G01S7/04, G01S7/38|
|May 30, 2007||AS||Assignment|
Owner name: NAVY, UNITED STATES OF AMERICA AS REPRESENTED BY T
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:BURKHOLDER, SCOTT;REEL/FRAME:019507/0413
Effective date: 20070529
|Nov 20, 2009||AS||Assignment|
Owner name: GBL SYSTEMS CORPORATION, CALIFORNIA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:BUSCEMI, JAMES;REEL/FRAME:023558/0034
Effective date: 20090728
Owner name: GBL SYSTEMS CORPORATION, CALIFORNIA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:DARK, JAMES;REEL/FRAME:023558/0032
Effective date: 20090728
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